Computed tomography (CT) represents the main research area of the Section on Neuroradiology and Computed Tomography. Our experience with a variety of scanners (two head and two body EMI-Scanners at NIH and two ACTA-Scanners at the GTU Medical School) is large and increasing. Preliminary feasibility tests to build a new type of CT device which will use protons rather than x-rays are under way. A number of mathematical and physical projects have been completed or are being carried out: simultaneous dual-energy CT using an originally designed split detector; studies of slice geometry in CT; mathematical and physical experimental analysis of a variety of CT artifacts; mathematical improvements of interpolation procedure in CT reconstruction. Clinical studies include brain, spinal cord and orbit CT research on: normal controls, demyelinating diseases, atrophic processes (including Parkinson and Huntington diseases), postradiation necrosis, oculo-orbital lesions. BIBLIOGRAPHIC REFERENCES: Pratt, R.A., Di Chiro, G. and Weed, J.C., Jr.: Cerebral necrosis following irradiation and chemotherapy for metastatic choriocarcinoma. Sur. Neurol. 7: 117-120, 1977. Peylan-Ramu, N., Poplack, D.G., Blei, C.L., Herdt, J.R., Vermess, M. and Di Chiro, G.: Computer assisted tomography in methotrexate encephalopathy. J. Comput. Assisted Tomogr. 1: 216-221, 1977.